Why AI could fail even after several attempts
Dear Dr Othieno, I need your help. my cow has been served three times without success. Last week, I called a vet to examine the cow but he said all results were negative meaning my dairy cross is fine. What could be making it not to conceive? I am using Artificial Insemination since I want to improve its genetics but I am now considering going for a bull which I am told rarely fails.
Thank you Mr Kamau for reaching out to us. First, I wish to reassure you that Artificial Insemination (commonly known as AI) has several advantages over using a bull. While the bull may spread diseases of the reproductive system from one farm to another, AI minimises this. AI is cheap and safe since you eliminate the cost of keeping a bull and safety of the people on the farm and even female animals. Artificial Insemination helps a farmer to cover more mileage in terms of genetics within a short time.
Did she ovulate? Is the first question vets ask themselves when dealing with a case of repeated inseminations? If there is no egg to be fertilised by the semen, you are labouring in vain. Anovulation is a condition where a cow doesn’t ovulate as expected (the ovaries do not produce an egg). The egg can still be produced but may fail to reach the uterus due to blocked oviducts, or the still it can reach the uterus but fail to attach onto the uterine wall as required due to various reproductive diseases. There are several bacterial, protozoan and viral diseases that affect the reproductive system and therefore result in infertility.
These diseases include Brucellosis, Trichomoniasis, Leptospirosis, Bovine Viral Diarrhoea etc. This is in addition to post birth conditions like retained placenta, mastitis and metritis. Respiratory and digestive conditions also negatively affect embryo development. Even if these hindrances were absent and the cow conceived; do not assume that you will get a calf after nine months. Early embryonic deaths are common. Embryos are sensitive to heat stress in their first week. Heat stress in common in high milk producers and is often worsened by hot weather conditions. Research shows that 20 per cent of embryos are lost within the first month and another 12 per cent in the next four weeks.
The farmer plays a critical role in Artificial Insemination because he is the link between the animal and inseminator. He is the one who observes the heat signs and calls the inseminator in good time. Timing is everything because the released egg by the female and the sperm have a lifespan. The sperm must stay in the female reproductive tract for some time before it gains the capacity to fertilise the egg. Thus it is recommended that the cow is inseminated between 4 – 16 hours after the onset of heat signs. Body condition which is dependent on nutrition is another key factor in conception. Animals with a poor body condition are unlikely to conceive. Zinc, copper, selenium and cobalt are required for reproduction. When animals do not receive supplementation, their fertility will be affected.
Semen is alive, poor handling and storage can lead to death. Semen is stored in liquid nitrogen at very low temperatures to maintain their viability. At the point of insemination they are “resurrected” through a process called thawing – dipping them in warm water for a specified period of time as recommended by the suppliers. If this is improperly done, they die. During this process, hygienic conditions should be maintained to avoid contaminating the semen. In short, poor handling or storage of semen reduces their viability and therefore AI success. Insemination is an art and science. Successful artificial insemination requires that the cow is in the right health condition and at an appropriate phase of the estrus cycle; that the farmer picks the heat signs and calls in an inseminator who does their job well.
[The writer works with the Kenya Tsetse and Trypanosomiasis Eradication Council, [email protected]]
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